Porous Polymer Matrix Catch Can

ABSTRACT

Disclosed is an oil catch can device employing a porous polymer matrix which filters and collects oil and other combustion byproducts typically found in “blow-by” gasses of an internal combustion engine. Employing a porous polymer matrix is a more effective means of filtering and collecting components of blow-by gasses due to the physical and chemical properties of the matrix. Various polymers can be used to produce the porous polymer matrix. By controlling the polymer type and particle size distribution of the particles that are sintered to create the matrix, filtration and adsorption can be maximized while maintaining a sufficient flow rate of gasses through the device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Patent Application: 62/908,553.

FIELD OF INVENTION

The present invention relates to oil catch cans used in conjunction with crank case ventilation systems for the removal of oils from air that travels through the system, termed “blow-by”.

BACKGROUND OF INVENTION

In practice, internal combustion engines exhibit leakage losses commonly referred to as “blow-by gases” due to incomplete sealing, for example, of the piston/cylinder path or valve guides in the cylinder head. If left unvented, these blow-by gases cause detrimental effects to the engine, for example, pressurization of the crankcase causing leaks and contamination of engine oil. At minimum, venting of blow-by gases to the atmosphere is required for proper operation and longevity of the engine. With the advent of modern emissions standards to reduce the environmental effect of venting products of combustion directly to atmosphere, blow-by gases are commonly scavenged from the crankcase, for example, using a vacuum source, and returned to the intake tract to be combusted. This is commonly referred to as the Positive Crankcase Ventilation (PCV) system

Blow-by gases are comprised of numerous products of combustion and including but not limited to, crankcase oil vapors, carbon particulate, water, unburnt fuel and gaseous products of hydrocarbon combustion. Venting blow-by gases to the intake tract can cause undesirable effects, for example, decreasing the resistance to detonation commonly referred to as “knock”, accumulating oil and sludge deposits throughout the intake tract, accumulating oil and sludge deposits on the intake valves which can reduce airflow volume into the combustion chambers, accumulating oil and sludge on heat exchangers commonly referred to as “intercoolers” decreasing their effectiveness, fouling of air mass measuring members and turbochargers.

In order to decrease the undesirable effects of venting blow-by gases to the intake tract of an engine, it is known to subject the flow of gases to a device intended to separate and accumulate the liquid components of blow-by. This type of device is commonly referred to as a “catch can”. Commonly, the catch can is placed in-between the crankcase vent and induction tract and is comprised of a hollow container. This hollow container allows the gases to expand and cool, causing liquid vapors to condense and pool at the bottom of the container. Incorporation of metal baffles or steel wool or sintered metal to further induce coalescence of liquid vapors is advantageous.

Previous disclosures teach the use of porous polymer or sintered metal matrices as a component of a system to assist in condensing atomized oil from blow-by gasses and returning them to the oil reservoir in the crankcase. Rather than return the condensed liquid components of blow-by gasses to the crankcase, it is advantageous to collect and isolate these components from the engine's oil supply thus reducing engine oil contamination from undesirable components of blow-by gasses.

This disclosure will teach the use of porous polymer matrices consisting of oleophilic polymers in a catch can system as a more effective means of extracting oil and other by-products of combustion from crankcase gasses.

SUMMARY

This disclosure is directed to oil catch can devices that force air, or “blow-by”, to travel through a Porous Polymer Matrix, which pulls the oil from the air and captures it. The Porous Polymer Matrix comprises a sintered porous polymer matrix. The polymer used to construct the matrix is oleophilic, which allows it to attract oil droplets suspended in the air through adsorption and hold captured oil within the volume of the matrix through absorption, as opposed to the condensing action of existing catch cans. Adsorption preceding absorption is more effective than condensation, with or without the use of coalescent media, in purifying the air, therefore reducing the downstream effects which can be damaging to the engine in the long run. These Porous Polymer Matrices are made through sintering processes. By controlling the polymer type and particle size distribution of the particles that are sintered to create the Porous Polymer Matrix, the absorption can be optimized.

A catch can with a Porous Polymer Matrix has an advantage in that that it is more effective at filtering oil droplets from crankcase gases than a traditional catch can.

SHORT DESCRIPTION OF THE FIGURES

FIG. 1: an exploded view of an embodiment of the catch can device displaying the Porous Polymer Matrix.

DETAILED DESCRIPTION

An embodiment of the invention comprises a chamber, which can be of any shape, consisting of at least 2 pieces, a lid and a main body. The chamber and lid can be constructed from any material that is impermeable to fluid including, but not limited to, stainless steel, aluminum, or polymer. The chamber and lid are constructed in such a fashion as to allow the lid to be attached to the chamber. The method of attachment includes, but is not limited to, interlocking threads, fasteners, and latches. The embodiment further comprises a Porous Polymer Matrix which is positioned inside the chamber. Porous Polymer Matrix is a sintered porous polymer matrix, in which the polymer is oleophilic, with a melt flow index less than 2 g/10 min. The average pore size can be between 10 and 300 microns. The Porous Polymer Matrix can be of any shape, as long as it will fit within the chamber and allow for the lid to attach to the chamber, creating a seal. In addition, the Porous Polymer Matrix should be seated within the chamber in such a way that forces air to flow through the Porous Polymer Matrix. In addition, the Porous Polymer Matrix should contain an interior hollow space that begins at the interior of the lid or interior main body and extends any distance towards the chamber floor or towards the opposite side wall of the interior main body. The embodiment further comprises a first aperture in the lid or main body, located within the hollow space in the Porous Polymer Matrix which allows for the passage of air. The embodiment further comprises a second aperture in the lid or wall of the chamber that allows for the passage of air. Thus, when assembled, the invention is incorporated into the PCV system of an internal combustion engine, allows for passage of air and crankcase blow-by gases from the exterior of the catch can, through the first aperture, into the hollow space within the Porous Polymer Matrix, through the Porous Polymer Matrix, exiting through the second aperture and returned to the intake tract to be combusted. By forcing the air through the Porous Polymer Matrix, the harmful products of combustion, including but not limited to, crankcase oil vapors, carbon particulate, water, unburnt fuel and gaseous products of hydrocarbon combustion are subjected to the oleophilic nature of the matrix, which allows it to attract oil based contaminant suspended in the air through adsorption and hold captured oil within the volume of the matrix through absorption. In conjunction, the matrix's structure filters non-oil based by products in the combustion gases, further isolating these contaminants from the engine's oil supply. This is an improvement on previous designs where the harmful products of combustion enter a single open chamber or chambers incorporating metal baffles, steel wool or sintered metal, designed to only slow liquid vapors and particulate causing condensation and coalescence in the chamber, without the added benefits of adsorption or absorption.

Another embodiment of the invention allows for the passage of air from the exterior of the invention, through the second aperture, into the chamber, through Porous Polymer Matrix into the hollow space within Porous Polymer Matrix exiting through the first aperture.

FIG. 1 shows a non-limiting example of an embodiment of a catch can device comprised of a Porous Polymer Matrix 5 housed inside a catch can 3. A cap 4 is secured to the top of the can 3 and a bottom 2 is secured to the bottom of the can 3, using o-rings 1 to create a tight seal. The inventive concept of having a Porous Polymer Matrix through adsorption to hold captured oil can be modified and used with any catch can known to those with skill in the art.

The particle size of the polymer that is used to manufacture the sintered Porous Polymer Matrix can ultimately determine the capability of the device to filter blow-by gases. Generally, when sintered together, smaller particles create a Porous Polymer Matrix with smaller pores and higher surface area, whereas larger particles create a Porous Polymer Matrix with larger pores and lower surface area. Similarly, if more particles of a given size distribution are compressed in a sintering mold of a given volume, the size of the pores in the diffusion matrix is reduced and the surface area is increased. Generally, flow rate of air permeation measured at a static back pressure and pore size of a porous polymer matrix have a direct relationship with flow rate increasing as pore size increases. Generally, a porous polymer matrix is more effective at filtering as pore size decreases. Consideration must be given to pore size selection for any given application as insufficient flow rate can result in excessive positive crankcase pressure which can be detrimental to an engine. Filtration should be optimized by choosing the smallest pore size which still allows for a sufficient flow rate to eliminate excessive crankcase pressure. The sufficient flow rate needed to eliminate excessive crankcase pressure will vary depending on the engine configuration.

Producing a Porous Polymer Matrix with the desired characteristics requires sintering polymer particles of a particular size range while maintaining partial separation between the particles during sintering so as to form pores between adjacent particles that ultimately will be fluidly connected to one another to form a network of passages extending throughout the Porous Polymer Matrix. There are many industry standards which can be used to determine the particle size of the loose particulate that is sintered to form the porous microchannel diffusion matrix. ASTM D6913-04(2009) is a standard for measuring the particle size diameter distribution of soil, but it can be used as the standard for determining the particle size diameter of other granular particles that will not reduce in size through vibration. Sieves of various sizes are used to separate particles by their diameter. Each gradation of particle diameter is weighed, and the weights are used to describe particle size distribution. A polymer particle size distribution in which 90% of the particles are between 20 and 3000 μm in diameter can be sintered to form a Porous Polymer Matrix that provides effective filtering of blow-by gases. More effective filtering can be obtained by sintering the Porous Polymer Matrix from particles having a particle size distribution in which 90% of the particles are between 20 and 1500 μm in diameter. Still more effective filtration and adsorption can be obtained by sintering the Porous Polymer Matrix from particles having a particle size distribution in which 90% of the particles are between 20 and 200 μm in diameter.

Any polymer that has a fractional melt can be sintered by a combination of pressure and/or heat. The viscosity of the polymer during the fractional melt is typically defined by its melt flow rate. Melt flow rate can be measured according to the technique described by ASTM D 1238. A melt flow rate less than 5 g/10 minutes is preferable for sintering because the polymer will have a viscosity that will bind the particles together while maintaining a porous structure. At melt flow rates higher than 5 g/10 minutes the polymer will liquefy, which is more suitable to injection molding or compression molding applications. More preferably, a melt flow rate less than 3 g/10 minutes will allow for a Porous Polymer Matrix to be manufactured with a reduced amount of meltback. Meltback is defined as a reduction in porosity and volume as a result of liquification of the polymer, which would reduce the volume of the Porous Polymer Matrix in an irregular fashion; though it would still be porous. Most preferably, a melt flow rate less than 1 g/10 minutes will greatly minimize meltback.

Polymers that work particularly well for a Porous Polymer Matrix are polyethylene, polypropylene, and polycarbonate. Even polymers without a traditional fractional melt can be sintered with the appropriate pressure and heat, as long as the powders can bind together without melt flow. Examples of polymers in this category are high molecular weight versions of polyethylene, which are commercially available.

Examples of polymers that work well are listed in the table below, along with relevant material properties. Table 1 is for illustrative purposes only and not meant to be limiting.

TABLE 1 Polymer and relevant properties. Sabic Lexan Profax 7823 GUR 4022-6 Property Polycarbonate Polypropylene UHMWPE Unit Standard Density 1.19 0.90 0.93 g/cm³ ASTM D 792/ISO 1183 Melt Flow Rate, 3.50 0.45 <0.1 g/10 ASTM D 300° C./1.2 kgf min 1238 Melt Temperature 320-345 120 130-135 ° C. ° C. ISO 3146 Tensile Stress, yld, 61.8 27.0 >17 MPa ASTM D Type I, 50 mm/min 638 Vicat Softening Temp, 154 NR 80 ° C. ASTM D Rate B/50 1525 Heat Deflection 137 88 42 ° C. ASTM D Temperature, 0.45 MPa, 648 6.4 mm, unannealed

In one or more embodiments, the Porous Polymer Matrix defines a network of pores having pore diameters in a range of from about 10-300 μm and the diffusion matrix has a porosity in a range of from about 30-60%. Pore diameters can be determined using imaging techniques such as Scanning Electron Microscope imaging. Porosity P can be determined using Equation 1 below, based on the total volume V of the diffusion matrix, including sintered particle volume and pore network volume (can be calculated based on the inner and outer diameters of the diffusion matrix and its length); the material density D of the particles; and the measured mass M of the diffusion matrix. Table 2 below provides the parameters used to determine the porosity of two illustrative diffusion matrixes based on Equation 1.

TABLE 2 Determination of Porosity of Porous Polymer Matrices Equation 1: Outer Inner Mass Density Diameter Diameter Length Volume Volume Porosity Polymer (g) (g/cc) (in) (in) (in) (in{circumflex over ( )}3) (cc) (%) Polypropylene 5.45 0.9 0.965 0.489 1.111 0.604 9.891 39% Polycarbonate 3.38 1.2 0.989 0.497 0.631 0.362 5.935 53%

The optimal pore size, porosity, outside diameter, inside diameter, length and number of pores will vary depending on the design of the internal combustion engine that the catch can will be connected to. Controlling these parameters allows the device to be tailored precisely to each application, altering the porosity and pore size to maintain effective filtering.

The foregoing description merely illustrates the invention and is not intended to be limiting. It will be apparent to those skilled in the art that various modifications can be made without departing from the inventive concept. Accordingly, it is not intended that the invention be limited except by the appended claims. 

What is claimed is:
 1. A Porous Polymer Matrix Catch Can that removes oil from the blow-by gases that travel through a Positive Crankcase Ventilation (PCV) system, the Porous Polymer Matrix Catch Can comprising: A Catch Can and a Porous Polymer Matrix, the Porous Polymer Matrix being comprised of a sintered polymer, the sintered polymer being comprised of particles having a size distribution in which 90% of the particles are in a range between 20 μm and 3000 μm in diameter before sintering and said particles having a Melt Flow Rate of less than 5 grams over 10 minutes, the Porous Polymer Matrix having an exterior surface and an interior surface, the sintered polymer forming a plurality of pores opening at the interior surface and a plurality of pores opening at the exterior surface and a plurality of channels within the Porous Polymer Matrix placing at least one or more of the plurality of pores opening at the interior surface in fluid communication with at least one or more of the plurality of the pores opening at the exterior surface, the Porous Polymer Matrix being positioned in such a way that the air from the Positive Crankcase Ventilation (PCV) system is forced through it; the Porous Polymer Matrix being housed in the Catch Can, the Catch Can being hollow and of any geometrical shape, whereby the blow-by-gases are produced by an internal combustion engine, whereby the blow-by gases enter the Catch Can, flow through the Porous Polymer Matrix and then exit the Catch Can, whereby oils from the blow-by-gases are removed by the Porous Polymer Matrix, and whereby the Catch Can is used in conjunction with the Positive Crankcase Ventilation (PCV) system.
 2. The Porous Polymer Matrix Catch Can of claim 1, where the sintered polymer comprising the Porous Polymer Matrix is selected from a group consisting of polypropylene, polyethylene, and polycarbonate.
 3. The Porous Polymer Matrix Catch Can of claim 1, where the sintered polymer comprising the Porous Polymer Matrix is a thermally resistant polymer.
 4. The Porous Polymer Matrix Catch Can of claim 1, wherein the Melt Flow Rate of the sintered polymer comprising the Porous Polymer Matrix is less than 3 grams over 10 minutes.
 5. The Porous Polymer Matrix Catch Can of claim 1, wherein the Melt Flow Rate of the sintered polymer comprising the Porous Polymer Matrix is less than 1 gram over 10 minutes.
 6. The Porous Polymer Matrix Catch Can of claim 1, wherein the sintered polymer comprising the Porous Polymer Matrix is formed from particles having a size distribution in which 90% of the particles are between 20 μm and 1500 μm in diameter.
 7. The Porous Polymer Matrix Catch Can of claim 1, wherein the sintered polymer comprising the Porous Polymer Matrix is formed from particles having a size distribution in which 90% of the particles are between 20 μm and 200 μm in diameter.
 8. The Porous Polymer Matrix Catch Can of claim 1, wherein the Porous Polymer Matrix has porosity in a range of from about 30% to about 60%.
 9. The Porous Polymer Matrix Catch Can of claim 1, wherein the pores formed in the Porous Polymer Matrix have a median pore diameter of from about 10 μm to about 200 μm. 